The present invention relates to a method and apparatus for detecting stress in an object in response to an applied load. It is often desired to determine stress in an object to which a working load has been applied. For example, it is desirable to determine the effect of the application of working loads on automobile suspension parts to determine whether, in use, there will be concentrations of stress.
Many methods have been utilised in the past, including utilising transparent models of the component part, applying a working load, and from the polarisation effects, determining the stress across the object. With such an arrangement, apart from the fact that the object itself is not being tested, but a replica thereof, it can be difficult to determine whether tension or compression is present in a particular area of the object and difficult to quantitatively determine the stress.
Another conventional way of testing for stress is the use of stress gauges which are attached to particular parts of the object under test. Clearly the stress gauges can only test for stress between two particular points and there are a limited number of points which one can examine in this way. An unusual configuration of stress concentration might be missed by such a method.